The present invention relates to gear shifting control in a parallel shaft gearbox, provided with an actuator.
It relates to a method for controlling a shift actuator with a sliding gear comprising a control element for controlling a shift fork responsible for disengaging and engaging pinions on a shaft of the gearbox, that receives the torque from a traction machine powered by the on-board electrical system of the vehicle. This control element is placed upstream of a mechanical spring-assist system. It is regulated in position by a DC actuating motor.
The invention also relates to a shift actuator comprising a control element for controlling a shift fork ensuring the disengaging and engaging of pinions on a shaft of the gearbox. This control element is regulated in position by a DC actuating motor supplied by an on-board electrical system of the vehicle equipped with a voltage modulation element. In this actuator, the control element is placed upstream of a mechanical spring-assist system, facilitating the engagement of the teeth of the sliding gear between those of the pinion.
The invention finds a preferred, but non-limiting, application on “robotic” type gearboxes, which operate as a manual gearbox with automatic shifting, without pinion synchronization mechanisms.
In internal gear shift control systems without synchronization mechanisms, sliding gears with flat teeth or “claws” are used, which abut against the teeth of the gear pinion to be engaged, before turning slightly in relation to the pinion so as to be able to engage between its teeth.
In order to attain the required levels of shifting comfort, shift-assist devices can be used, which implement a resistance spring, capable of storing energy when it compresses during the synchronization phase and releasing the energy at the conclusion of this phase, to facilitate the engagement of the pinion.
Publication FR 2 988 800 discloses a known system for actuating a sliding claw gear, comprising a rigid fork displacement fixture equipped with two arms engaged about a control shaft, so as to allow its own axial displacement along this shaft, under the control of an external element. The system further comprises a resistance spring, wrapped about the fork shaft between the two arms of the fixture and two retaining collars abutting between the ends of the spring and the arms of the fixture, so as to be able to slide with limited movement along the shaft. The spring stores the energy supplied by the actuator, when the teeth of the sliding gear and the pinion abut. The spring releases the energy when engagement is possible, by accelerating the fork. The acceleration obtained depends on the compression of the spring, and therefore on the torque transmitted by the electric motor during the phase when the teeth abut.
During a gear change, it is important to minimize the time taken by all necessary operations required for smooth shifting.